I have also used canvas, and it has worked out fine for me so far, worth a try if you have some on hand or can find it cheap. I found a lot of it for $2.00, so have done several bows with it, and it doesn't look too bad either. Definitely doesn't enhance performance, but I haven't lifted any splinters yet, so it has given me a little peace of mind. I know red oak is pretty good in tension, but not as much in compression, so be careful not to overpower the belly. I wonder if rawhide, sinew or hickory might be too much for red oak, not really sure. I would probably go with the paper bag, silk or linen, imho.